Tech Briefs

A new tool to help policy makers better assess the costs and benefits of building dams could change the way nations decide to develop hydroelectric power.

The Integrative Dam Assessment Modeling tool, or IDAM, uses an interdisciplinary approach to simultaneously evaluate the distribution of biophysical, socioeconomic and geopolitical impacts of dams, according to one of the model’s creators, Bryan Tilt, associate professor of anthropology at Oregon State University.

The model was designed as a decision-support tool that policy makers can use to understand holistically the impacts, costs and benefits of building a dam in any area. In July, researchers at OSU who developed the model presented the tool in Washington, D.C., to a group of policy-makers, government agencies and environmental organizations from the U.S., China and Southeast Asia.

The dam assessment tool measures the costs associated with a proposed dam development project and the possible benefits. Each of the diagrams in the tool consists of 27 individual indicators of the effects of dam construction, divided into socioeconomic, geopolitical and biophysical themes. For example, factors such as habitat restoration costs can be weighed, along with loss of income to local people and access to clean drinking water.

Tilt said the impetus for this dam modeling project followed the publication of the World Commission on Dams in 2000, which called for more equitable and sustainable decision-making with respect to large dams. In 2007, the National Science Foundation funded the research by OSU and its collaborators to develop and test this dam assessment tool.

The Institute of Electrical and Electronics Engineers Inc. announces a new standard, “IEEE Guide for the Application of Turbine Governing Systems for Hydroelectric Generating Units.”

There is a heightened awareness within the electric utility industry of the importance of the effective application of governing systems for dynamic stability, IEEE says. The need exists to provide guidance in the effective governing system application for a better understanding among users.

IEEE 1207 is intended to complement IEEE standard 125, providing application details and addressing the impact of plant and system features on hydroelectric unit governing performance. It provides guidance for the design and application of hydroelectric turbine governing systems.

IEEE is a professional association dedicated to advancing technological innovation and excellence.

An analysis of data regarding greenhouse gas emissions from hydroelectric reservoirs, published in August in the online version of the journal Nature Geoscience, posits that these human-made systems emit about one sixth of the carbon dioxide (CO2) and methane (CH4) previously attributed to them.

Prior studies based on more limited data cautioned that hydro reservoirs could be a significant and large source of both CO2 and CH4 to the atmosphere.

Through an analysis of 85 globally-distributed hydroelectric reservoirs, the authors revealed that these systems emit 48 million metric tons of carbon annually, a downgrade from earlier estimates of 321 million metric tons. In addition, hydroelectric reservoirs are responsible for less than 16 percent of the total CO2and CH4 emissions from all types of human-made reservoirs combined.

“Our analysis indicates that hydroelectric reservoirs are not major contributors to the greenhouse gas problem,” comments Dr. Jonathan Cole, a limnologist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y., and one of the paper’s authors. “But there are some caveats. To date, only 17 percent of potential hydroelectric reservoir sites have been exploited, and impacts vary based on reservoir age, size, and location.”

CO2 and CH4 are two of the main greenhouse gases created by human activities. Both also are produced naturally, particularly in wetlands and lakes.

ASME releases handbook on energy and power generation

The American Society of Mechanical Engineers announces availability of the Energy and Power Generation Handbook.

This book is a compendium of 32 articles and textbook chapters reflecting the latest expert opinions on the production and use of energy around the world, according to ASME.

Power generation is covered from all known sources, including hydropower, tidal and waves, solar, wind, bio energy, waste material, geothermal, fossil, petroleum, gas and nuclear. Chapters also are devoted to nanotechnology and the role of NASA in photovoltaic and wind energy.

Dr. K.R. Rao, P.E., edited the book, which was written for researchers, practicing engineers, economists and advocacy planners. More than 50 experts from around the world contributed to this book, with authors representing Siemens Energy, the Electric Power Research Institute, Babcock & Wilcox and the Indian Institute of Technology.

ASME is a not-for-profit professional organization that enables collaboration, knowledge sharing and skill development across all engineering disciplines.

— To order this book for $240 for ASME members and $300 for non-members, visit asme.org/kb/books.

Authored by Worldwatch Institute Senior Fellow Janet Sawin, in collaboration with a global network of research partners, the report shows that in 2010 renewable energy supplied an estimated 16 percent of global final energy consumption and delivered close to 20 percent of global electricity production. Renewable capacity, including hydropower, now comprises about a quarter of total global power-generating capacity. Including large and small hydropower (an estimated 30,000 MW added in 2010), renewable energy accounted for about 50 percent of total added power-generating capacity in 2010.

The report was commissioned by the Renewable Energy Policy Network for the 21st Century, or REN21.

ASCE releases book on sediment and dam removal

The American Society of Civil Engineers offers Sediment Dynamics upon Dam Removal.

This book provides guidance, documentation and field results for the numerical and physical modeling of sediment movement when dams are removed from waterways. When dam removal is being considered, the impounded sediment collected behind the dam poses its own set of environmental and technical problems. This manual addresses issues such as the behavior of stored sediment and overall stream geomorphology after a dam is removed.

Drs. Athanasios N. Papanicolaou and Brian D. Barkdoll, P.E., edited this 192-page book. Content in the book is geared toward watershed and river managers, environmental engineers, consultants and researchers.

Production of this book was sponsored by the task Committee on Sediment Dynamics Post-Dam Removal of the Environmental and Water Resources Institute of ASCE.

ASCE represents more than 140,000 members of the civil engineering profession worldwide.

This guide covers the basics of bearings and bearing arrangements, including instructions for mounting bearings, bearing units, housings and seals. The handbook also describes safe and skillful maintenance practices that can help extend bearing service life, reduce machine downtime and minimize unplanned maintenance activities.

The handbook, intended for maintenance professionals, is divided into 14 chapters that cover: